Gas chromatography method and apparatus

ABSTRACT

A gas chromatograph which divides the effluent stream from its column into two portions. One portion is for obtaining a conventional record with peaks which indicate the various compounds in the effluent of the colunn. The other portion of the divided effluent is directed through a nozzle and against a strip, that may be coated, for retaining the effluent while the strip is moved in synchronism with the conventional record. The strip may be matched against the record afterward so that individual peaks may be identified by direct analysis of the trapped effluent on the strip.

United States Patent Bednarski 1 Oct. 3, 1972 [54] GAS CHROMATOGRAPHY METHOD AND APPARATUS [72] Inventor: Valery N. Bednarski, c/o Texaco Inc., P.O. Box 425, Bellaire, Tex. 77401 [22] Filed: Sept. 10, 1970 [21] Appl. No.: 71,165

[52] US. Cl. ..55/67, 73/23.], 55/386 [51] Int. Cl ..B0ld 53/04, BOld 15/08 [58] Field of Search ..210/31, I98; 73/23.l; 55/67, 55/ 197, 386

[56] References Cited UNITED STATES PATENTS 3,128,619 4/1964 Lieberman ..73/23.l 3,376,694 4/1968 Owens et al. ..55/67 FOREIGN PATENTS OR APPLICATIONS 916,919 1/1963 Great Britain ..55/386 Primary Examiner-John Adee Attorney-Thomas H. Whaley and Carl G. Ries ABS'I RACT A gas chromatograph which divides the effluent stream from its column into two portions. One portion is for obtaining a conventional record with peaks which indicate the various compounds in the eifluent of the colunn. The other portion of the divided effluent is directed through a nozzle and against a strip, that may be coated, for retaining the effluent while the strip is moved in synchronism with the conventional record. The strip may be matched against the record afterward so that individual peaks may be identified by direct analysis of the trapped effluent on the strip.

3 Claims, 2 Drawing Figures PATENTEDIIBT3 I9 Y 3.695.003

SHEET 2 BF 2 I u. u D

Q III III B III GAS CHROMATOGRAPHY METHOD AND APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention concerns gas chromatography, in general. More specifically, it relates to a procedure and/or apparatus that permits continuous trapping of the effluent from a gas chromatograph column. The trapping is done in synchronism with the recording of a particular conventional characteristic. In this manner the effluent compounds may be analyzed with easy and direct identification against the record peaks from the conventional recording.

2. Description of the Prior Art In the art of gas chromatography, in general, there has been a need for direct identification of particular components (compounds) as they are eluted from the chromatograph column so that they may be better identified in relation to the record peaks which reveal their individual presence. While there have been some suggestions in the past for carrying out a separation of the individual compounds in the effluent from a chromatograph separation column, they have not met or overcome the difficulties involved in separately trapping and identifying the particular portions of the effluent that contain given compounds from a total sample run.

Thus, one prior procedure has been to divide up the effluent of a chromatograph column by sampling separate portions in individual containers and thereafter making analyses and identification of the portions. However, such procedure has involved taking a second run of the sample that was run through the chromatograph, in order to match given effluent portions with particular peaks on the chromatograph record. Such procedure was time consuming, and the matching of particular components of the total, stream was not as accurate as might be desired. Also, the manipulation required in taking separate samples during a run was difficult, especially where a number of closely eluted compounds were to be separated.

Consequently, it is an object of this invention to provide an improved method and apparatus that permits the continuous trapping of a portion of the effluent from a chromatograph column, while the other portion is run through the chromatograph to provide the usual record. The continuous trapping is done in synchronism with recording of the particular ordinary characteristic so that particular portions of the trapped effluent may be matched against the record of the chromatograph.

SUMMARY OF THE INVENTION Briefly, the invention relates to gas chromatography wherein a sample is separated into components that are spaced apart chronologically at the output from a separation column. It concerns a method of trapping whereby said retained components may berelated to said record peaks.

Once more, briefly, the invention concerns gas chromatography wherein a sample is separated into components by passage through a column which delays the passage of some of the components more than others, and wherein a chromatograph or record is made having peaks for said components. The invention concerns a combination which comprises means for dividing the output of said column into at least two branches one for use in making said record, and a nozzle connected to the other of said branches. It also comprises a strip of aluminum foil having a thin coating of silica gel thereon, and a wheel having a'flat perimeter for attaching said coated strip thereon. The said wheel is located with said perimeter close to said nozzle for directing the effluent from said column against the surface of the wheel with said strip thereon. And, the said wheel has a predetermined diameter and is driven in synchronism with said record whereby said components (trapped in said thin coating) may be directly matched with said peaks on said record.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and benefits of the invention will be more fully set forth below in connection with the best mode'contemplated by the inventor of carrying out the invention, and in connection with which there are illustrations provided in the drawings,

wherein:

FIG. 1 'is a schematic illustration showing apparatus according to the invention; and

FIG. 2 is a graph illustrating a conventional chromatograph record, with a trapping strip according to this invention attached thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, it is pointed out that there are schematically illustrated some relevant elements of a conventional chromatograph. These include an oven 11 which is for maintaining a predetermined temperature surrounding a column 12. The column contains usual materials (not shown) that act on the sample which in turn is driven by a carrier gas, so as to delay the elusion of different components of the sample for different time periods, at the output end of the column.

On top of the oven 11, there is an insulation block 15 for providing heat insulation between the oven and a passage-way connection block 16,. Block 16 has internal passage-ways (not shown) for joining the input connections from a carrier gas inlet 17 and an injection conduit 18, through which the sample is introduced.

The carrier gas, and sample, flow into the column 12 D and out at the output end thereof (left hand side as illustrated in FIG. 1). This effluent goes to a flow splitting connection (not shown) in the block 16. Such split sends one portion of the effluent out through a pipe 22 that carries this portion to a conventional detector, e. g., an ionization detector.

The remaining portion of the effluent stream from column 12 flows out into a nozzle tipped pipe 23. This has at its output end a hypodermic needle 24 which acts to direct this portion of the effluent through the open end of the needle onto the surface of a strip 28.

The strip 28 may. be constructed of various materials. For example, it could be chromatographic paper which is treated to adsorb the compounds eluted more readily. Also, it is contemplated that it could be untreated paper tape. Similarly, it would be a paper strip that is coated with a thin layer of adsorbent material such as silica gel or other solids used in gas or thin layer chromatography.

It will also be appreciated that either coated or uncoated material for the strip 28 might be a transparent material so that compounds trapped thereon could be examined by infra-red or ultra-violet spectroscopy without removal from the tape. Also, if the adsorbed compounds are examined by internal reflection infrared spectroscopy, a foil tape such as aluminum or heavily anodized aluminum may be used. Furthermore, it is contemplated that fiberglass tapes coated with a silicon adhesive and with or without a layer or silica gel should lend itself to subsequent high temperature treatment to evaporate the trapped compounds into a mass spectrometer system.

The strip 28 is attached in any feasible manner onto the outer periphery of a wheel 29. The wheel 29 is constructed with a flat outer or peripheral surface, so that the strip 28 may be readily attached so as to lie flat thereagainst.

The wheel 29 is driven in rotation by a motor 30 that is preferably a synchronous motor. In any event, the wheel speed is synchronized with the travel of a chart 36 (FIG. 2) upon which a record is made by the chromatograph. The wheel 29 and motor 30 are supported in any feasible manner, such as by having a brace arm 33 which extends from surrounding support structure (not shown).

FIG. 2 illustrates a typical chart 36. It has a curve 38 drawn thereon from running a sample through the chromatograph column 12. The curve will ordinarily have a plurality of peaks 37 that are formed on the record as various components or compounds of the sample that is run through the chromatograph, appear. There is also shown the strip 28 that has been laid down onto the chart 36 in such a manner as to have the locations of components, as eluted from the column, placed in vertical alignment with the corresponding peaks 37 of the chart. This may easily be done by marking a beginning point on both the chart 36 and the strip 28, and then by placing the strip 28 with its mark in transverse alignment with the mark on the chart.

By thus aligning the strip 28, which has trapped thereon the various components of the eluted sample from the column 12, in correspondence with the peaks 37 of the chart 36, it is possible to physically identify the location of the components or compounds. Thereafter, using any of the techniques mentioned above, each particular component or compound may be analyzed as desired. For example, some of the surface of the strip 28 may be scraped off at particular locations corresponding to given peaks, and the scrapings taken for analysis.

METHOD A method according to the invention will be described in connection with both figures of the drawings. It will be appreciated that the method may be carried out with any feasible structure which is not necessarily the same as, or the mechanical equivalent of the structure illustrated and described above, in connection with the apparatus combination of the invention.

It will be noted that the method relates to gas chromatography of the type where a sample is separated into components that are spaced apart chronologically at the output from a separation column. The method involves trapping of the effluent at the output of said chromatograph, e.g., the column 12 of the FIG. 1 illustration. The trapping is accomplished with a physical separation of the components or compounds that corresponds to the spacing of peaks on a graphic record that is taken when a chromatograph run is made.

Thus, the method comprises the following steps:

I. The directing of some of the efiluent from the column against a trapping medium which is moved so as to space the effluent along the medium on a time axis as it is eluted from the column. Such directing of effluent from the column is done by having a nozzle, such as the needle 24, that is directed toward the surface of a moving strip, e. g., strip 28. The strip is preferably coated so as to retain some of the effluent as it is directed against the surface.

. The step of moving the surface (i.e., the strip 28 mentioned above) in direct proportion with the movement of the graphic record (e.g., chart 36) will cause a spacing of the components or compounds as they are eluted along the trapping strip. Therefore, they may be directly correlated with the peaks of the chromatograph record, e.g., record 36 illustrated in FIG. 2.

3. Another step of the invention is that of analyzing the retained components for identification thereof. This may be accomplished in various ways as already indicated above. For example, by scraping off the surface of the strip which has the coating thereon and then analyzing the scrapings for determination of the eluted compound or component of the sample. Other ways of analyzing the eluted components might involve such techniques as direct examination by infra-red or ultra violet spectroscope analysis, without removing the components from the tape. It might sometimes be preferable to remove the components of the effluent from the trapping material such as silica gel, by solvent extraction prior to the examination or other analysis.

While the invention has been described above in considerable detail in accordance with the applicable statutes, this is not to be taken as in any way limiting the invention but merely as being descriptive thereof.

I claim: I

1. ln gas chromatography wherein a sample is separated into components that are spaced apart chronologically at the output from a separation column,

a method of trapping the effluent at said output with a physical separation corresponding to the spacing of peaks on a graphic record of a characteristic of said effluent, which comprises the steps of directing one portion of said effluent to a chromatographic detector and making a record thereof,

directing a second portion of said effluent into impringement against a moving surface and permanently retaining some of said components thereon, and

moving said surface in direct proportion with said graphic record whereby said retained components may be related to said record peaks after completion of said graphic record. 2. The invention according to claim 1, further including the step of analyzing said retained components to identify them.

3. ln gas chromatography wherein a fluid mixture is separated into components by passage through a column which delays the passage of some of the components more than others,

the combination comprising means for making a chromatograph having peaks for said components,

means for dividing the output of said column into at least two branches one for use in making said chromatogram,

a nozzle connected to the other of said branches,

H050 UNKTED STATES PATENT OFFiCE 6 CERTIFICATE OF CORRECTION Patent No. 3, 95, 3 Dated October 3: 97

Inventor) VALERY N. BEDNARSKI It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the Patent Front Page,

under "Name of the Inventor(s)' please insert [73] As signee: Texaco Inc., New York, N.Y.

Signed and sealed this 12th day of February 1974.

(SEAL) Attest:

EDWARD M.FLET( IHER,JR. c. MARSHALL DANN Attestlng f r Commissioner of Patents 

2. The invention according to claim 1, further including the step of analyzing said retained components to identify them.
 3. In gas chromatography wherein a fluid mixture is separated into components by passage through a column which delays the passage of some of the components more than others, the combination comprising means for making a chromatograph having peaks for said components, means for dividing the output of said column into at least two branches one for use in making said chromatogram, a nozzle connected to the other of said branches, a strip of aluminum foil having a thin coating of silica gel thereon, a wheel having a flat perimeter for attaching said coated strip thereon, said wheel being located with said perimeter close to said nozzle for directing the effluent from said column against the surface thereof with said strip thereon, said wheel having a predetermined diameter, and means for driving said wheel in synchronism with said chromatogram whereby said fluid components trapped in said thin coating may be directly matched with said peaks on said chromatogram. 